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THE OFFICIAL ASE STUDY GUIDE ASE Transit Bus Tests

The Official aSe S G ASE Transit Bus Tests

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ASE Transit Bus Tests
ASE TrAnSiT BuS TESTS
ASE TrAnSiT BuS STudy GuidE Page 3
OvErviEw
Introduction The Official ASE Study Guide for Transit Bus Tests is designed to help technicians prepare for the ASE certification tests. This guide includes detailed information on the tests which cover technology found in today’s transit buses. The task list for each test, found in the following pages, should help you review your technical knowledge. Your focus should be on less familiar topics. This should make it easier to select additional reference materials that will help you prepare for your test(s).
ASE voluntary certification helps technicians prove their abilities to themselves, to their employers, and to their customers. By passing the tests and submitting appropriate work experience, you will earn the most valuable credential available to transit bus technicians. Because the tests are challenging, you’ll have the satisfaction of knowing you are among the elite in your profession. What’s more, these credentials are recognized throughout the U.S.
Certified technicians promote customer trust and improve the image of the industry. And trust and professionalism are the first steps to a better, more prosperous business.
ASE encourages you to take the tests and to join the proven pros who wear the ASE Blue Seal of Excellence®.
How Do I Become Certified? There are eight tests in the Transit Bus certification series. If you pass one or more test(s), and have at least two years of hands-on working experience in transit bus repair (appropriate training may substitute for up to one year of experience), you will become certified as an ASE Transit Bus Technician.
If you pass test H1 or H2, plus H3 through H8, and meet the work experience requirement, you will earn certification as a Master Transit Bus Technician.
Some of these tests are prerequisities for the Advanced Level tests. If you are currently certified in Diesel Engines (A9, H2, S2, or T2) and Electrical /Electronic
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Systems (A6, H6, S6, or T6), you are eligible to take the Advanced Level (L2) Electronic Diesel Engine Diagnosis Specialist test.
Your test results will be emailed to you immediately following your testing appointment. Results will not be given over the phone nor will they be released to anyone without your written permission. If you fail a test, you must wait 30 days from the test date before you can purchase it again.
Certification credentials are valid for five years. Recertification ensures certified technicians are seen as up-to-date in their profession. If you have been certified in an area for almost five years, it is time to register for the corresponding recer- tification test. Most recertification tests are about half the length of the initial certification tests.
Transit Bus Tests This Study Guide contains Test Specifications, Task Lists, and sample questions for the following ASE tests: • Compressed Natural Gas Engines (Test H1) • Diesel Engines (Test H2) • Drive Train (Test H3) • Brakes (Test H4) • Suspension and Steering (Test H5) • Electrical/Electronic Systems (Test H6) • Heating, Ventilation, & A/C (Test H7) • Preventive Maintenance & Inspection (Test H8)
ASE also offers certification in Automobile/Light Truck, Medium/Heavy Truck, Truck Equipment, School Bus, Maintenance & Light Repair, Collision Repair/ Refinish, Parts Specialist and Advanced Level specialties. Separate guides are available for each test series.
For full information on ASE testing as well as downloadable Study Guides and other test preparation resources, visit www.ase.com.
Who Writes the Questions? Working professionals from the service industry with expertise in the test topic write the questions, which are entirely job-related. The questions are designed to test knowledge of the skills that you need to know in servicing transit buses; theoretical knowledge is not covered.
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Each question has its roots in an ASE “item-writing” workshop where working bus technicians, technical educators, transit agency directors, and service representatives from parts and equipment manufacturers meet to share ideas and translate them into test questions. Each test question must survive review by all members of the group. The questions are written to mirror practical problems relevant to the diagnosis and repair performed by technicians in their day-to-day work.
After being written, all questions are pre-tested and quality-checked on a national sample of technicians. Those questions meeting ASE standards of quality and accuracy are then included in the scored sections of the tests; those that do not are redrafted or discarded altogether.
How Do I Prepare for the ASE Tests? The most important thing you can do is become familiar with test content and question formats.
How Long are the Tests?
* Certification tests include 10 research questions that are not counted for score. Since you don’t know which questions those are, you need to answer every question. You must have passed the certification test once to be eligible for the shorter recertification test.
Transit Bus Tests 2021 Certification Tests Recertification Tests
Name Number of questions
Testing time
H1 Compressed Natural Gas Engines 60* 1.25 hrs 25 30 mins
H2 Diesel Engines 60* 1.25 hrs 25 30 mins
H3 Drive Train 50* 1 hr 20 30 mins
H4 Brakes 60* 1.25 hrs 25 30 mins
H5 Suspension and Steering 55* 1.25 hrs 23 30 mins
H6 Electrical / Electronic Systems 60* 1.5 hrs 25 45 mins
H7 Heating, Ventilation, & A/C 50* 1.25 hrs 20 45 mins
H8 Preventive Maintenance & Inspection
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The Test Specifications in this booklet describe the content covered by each test. The Task Lists detail the actual work performed by technicians in each specialty area. Together, these are the blueprint for writing and assembling the ASE tests.
Each question on the test relates to a particular task or set of tasks in the task list. Therefore, review the task list, thinking about whether you know how to perform each task listed.
All questions are multiple-choice. The sample questions in this Study Guide are examples of the five types of questions on the test. Note there are different instructions for some question types.
Read each question carefully so that you understand exactly what is being asked. Each question tests a specific diagnostic or repair problem and has only one correct answer.
To summarize, we suggest the following steps be taken: Step 1. Carefully read the Test Specifications for each test you will attempt. Step 2. Study the Task List for each area. Step 3. Go over the sample questions to become familiar with each question type. This is very important! Step 4. Review steps 1 through 3 and identify the skill areas where you need additional study.
Getting Started Registration information is available at www.ase.com.This site shows testing locations and provides other important information, including an electronic version of all ASE Study Guides.
While on the ASE website, take a moment to create your own myASE account (if you do not already have one), which will allow you to register for tests, make test appointments, and have direct access to all your personal ASE certification information. Should you have questions that the website does not answer, you can reach our helpful customer
service staff at [email protected] or 800-390-6789.
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Issued Photo ID
Leave in locker-- aBooks aCalculator aCoat aCell Phone aSmart Devices aWallet aKeys
ASE TrAnSiT BuS STudy GuidE Page 7
At the Test Center—Some Tips Try to be well rested on exam day. Allow extra time to find parking and the Test Center office. Late arrivals may be turned away by Test Center staff. If you cannot take a test because you are late, you will forfeit your test fees.
Bring your Admission Ticket and unexpired, government-issued photo ID with you. Books, notes, calculators, and electronic devices (including cell phones) will not be permitted in the test room. You will be assigned a locker to store personal items. Most test centers have airport-level security procedures for all candidates, so be prepared for “wanding” or other security checks.
You will receive scratch paper and pencils, and for certain advanced level tests, a printed reference booklet. Each test appointment begins with a short tutorial on the operation of the testing platform. You may also preview the platform online at www.ase.com/asedemo before you arrive at the Test Center.
Each test has a time limit, as listed in the chart on page 5. After you start your test, the computer screen will continuously display the amount of time left. If you finish early, you can either review your answers or end the test and continue to the next test (if you are taking more than one). Once you submit a test for scoring, you cannot go back and review it. If you are taking several tests and need a short break, take it between tests. Take your break when you reach the screen that asks if you are taking additional tests. Do not take a break during a test as the test clock will continue to run.
If a question is difficult, mark the answer that you think is correct and flag the question using the on-screen button. Then go on to the next question. When you have finished the test, you may have time to go back to the flagged questions. Your score is based on the number of correct answers, so you should try to answer every question.
When you finish your last test, you will be given a short customer satisfaction survey. After you complete the survey, inform the staff and leave. When you check your email, your test results will be waiting for you! If you need a paper copy right away, ask the staff to print your results before you leave the test center.
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Test Content and Sample Questions To help you prepare, each section begins with the Test Specifications, which will list the main categories covered and the number of test questions, as well as the percentage of the test devoted to each topic.
The Task List describes the work activities a technician should be able to perform. This list was developed by working technicians and technical experts and will provide a valuable checklist telling you what you should know for the test.
The number of tasks listed does not equal the number of questions. Although every question relates to at least one listed task, some tasks may not appear on the test. Some complex tasks may be covered by several questions. Some questions may cover multiple simple tasks. The main goal of the list is to describe what is done on the job; any task on the list may be covered on the test.
Sample questions follow the Task List. Although these specific questions will not appear on tests, they are in the same format as actual test questions. The ASE tests employ several types of multiple-choice questions. Note that some questions have special instructions; the same instructions will appear with similar questions on the ASE tests.
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TEST SpEcificATiOnS And TASk LiST cOmprESSEd nATurAL GAS (cnG) EnGinES
(TEST H1)
Content Questions Percentage Area in Test of Test A. General Engine Diagnosis 9 18% B. Cylinder Head and Valve Train Diagnosis and Repair 4 8% C. Engine Block Diagnosis, Repair, and Overhaul 4 8% D. Lubrication and Cooling Systems Diagnosis and Repair 4 8% E. Air Induction and Exhaust Systems Diagnosis and Repair 7 14% F. Fuel System Inspection, Diagnosis, and Repair 14 28% G. Starting and Charging System Diagnosis and Repair 4 8% H. Ignition System Inspection Diagnosis, and Repair 4 8%
Total 50 100%
A. General Engine Diagnosis (9 questions) 1. Verify the complaint, check for and retrieve fault codes, and road test vehicle; review
operator service request and past maintenance documents (if available); determine further diagnosis.
2. Inspect engine assembly and engine compartment for natural gas, oil, coolant, exhaust, or other leaks; determine needed repairs.
3. Inspect engine compartment wiring harness, connectors, seals, and locks; check for proper routing and terminal/connector condition; determine needed repairs.
4. Listen for and diagnose engine noises; determine needed repairs. 5. Check engine exhaust for odor, smoke, or excessive temperatures; determine
needed repairs. 6. Perform fuel supply system tests; check fuel for contamination and consumption;
determine needed repairs. 7. Perform air intake system restriction and leakage tests; determine needed repairs. 8. Perform intake manifold pressure tests; determine needed repairs. 9. Perform exhaust backpressure and temperature tests; determine needed repairs. 10. Diagnose crankcase pressure concerns; perform applicable tests; determine needed
repairs.
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11. Diagnose no-crank, cranks but no-start, hard start, and starts and stalls problems; determine needed repairs.
12. Diagnose surging, rough operation, misfiring, low power, slow deceleration, slow acceleration, and shutdown problems; determine needed repairs.
13. Isolate and diagnose engine related vibration problems; check engine mounts; determine needed repairs.
14. Check cooling system for temperature protection level, contamination, coolant type, level, temperature, pressure, supplemental coolant additive (SCA) concentration, filtration, and fan operation; determine needed repairs.
15. Check lubrication system for contamination, oil level, condition, temperature, pressure, filtration, and oil consumption; determine needed repairs.
16. Check, record, and clear electronic diagnostic codes; monitor electronic data; determine needed repairs.
17. Perform visual inspection for physical damage and missing, modified, or tampered- with components; determine needed repairs.
18. Research applicable vehicle and service information, service precautions, and technical service bulletins (TSBs); determine needed actions.
19. Inspect accessory belts, drives, tensioners, and pulleys for tension and condition; determine needed repairs.
20. Perform engine compression test; determine needed repairs.
B. Cylinder Head and Valve Train Diagnosis and Repair (4 questions) 1. Remove, inspect, disassemble, and clean cylinder head assembly(s). 2. Inspect threaded holes, studs, and bolts for serviceability; repair or replace as needed. 3. Measure cylinder head-to-deck thickness; check mating surfaces for warpage
and surface finish; inspect for cracks and damage; check condition of coolant and oil passages; inspect core and gallery plugs; repair as needed.
4. Inspect valves, guides, seats, springs, retainers, rotators, locks and seals; determine serviceability and needed repairs.
5. Inspect spark plug threads and seats; determine needed action. 6. Inspect, reinstall or replace valve bridges (crossheads) and guides; adjust bridges
(crossheads). 7. Clean components; reassemble, check, and install cylinder head assembly. 8. Inspect, measure, reinstall, or replace pushrods, rocker arms, rocker arm shafts, and
rocker arm shaft supports for wear, bending, cracks, looseness, and blocked oil passages; determine needed repairs.
9. Inspect, measure, and adjust valve clearances.
C. Engine Block Diagnosis, Repair, and Overhaul (4 questions) 1. Remove, inspect, service, and reinstall pans, covers, breathers, gaskets, and seals. 2. Disassemble, clean, and inspect engine block for cracks; check mating surfaces
for damage or warpage and surface finish; check deck height; check condition of coolant and oil passages, core, and gallery plugs; inspect threaded holes, studs, dowel pins and bolts for serviceability; service, reinstall or replace as needed.
3. Inspect cylinder sleeve counterbore and lower bore; check bore distortion; determine needed service.
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ASE TrAnSiT BuS STudy GuidE Page 11
4. Inspect and measure cylinder walls or liners for wear and damage; determine needed service.
5. Reinstall or replace cylinder liners and seals; check and adjust liner heights. 6. Inspect in-block camshaft bearings for wear and damage; replace as needed. 7. Inspect, measure, reinstall or replace in-block camshaft; measure and adjust endplay;
inspect, measure, reinstall or replace cam followers (if applicable); inspect, measure, reinstall or replace camshaft tappets (if applicable).
8. Clean and inspect crankshaft and crankshaft journals for surface cracks and damage; check condition of oil passages; check passage plugs; measure journal diameters; check mounting surfaces; determine needed action.
9 Inspect, reinstall or replace main bearings; check cap fit and bearing clearances; check and correct crankshaft endplay.
10. Inspect, reinstall, and time the drive gear train (check timing sensors, gear wear and backlash of crankshaft, camshaft, auxiliary drive, and idler gears); service shafts, bushings, and bearings.
11. Clean, inspect, measure, reinstall or replace pistons, pins, and retainers. 12. Measure piston-to-cylinder wall clearances. 13. Check ring-to-groove clearances and end gaps; install piston rings. 14. Identify piston, connecting rod bearing, and main bearing wear patterns that indicate
connecting rod and crankshaft alignment or bearing bore problems; check bearing bore and bushing condition; determine needed repairs.
15. Assemble pistons and connecting rods and install in block; check piston height; replace rod bearings and check clearances; check condition, position, and clearance of piston cooling jets (nozzles).
16. Inspect and measure crankshaft vibration damper; determine needed actions. 17. Inspect, install, and align flywheel housing. 18. Inspect flywheel or flexplate (including ring gear) and mounting surfaces for cracks,
wear, and runout; determine needed repairs.
D. Lubrication and Cooling Systems Diagnosis and Repair (4 questions) 1. Verify engine oil pressure and temperature; check operation of pressure/temperature
sensors/switches, pressure gauge, and sending unit. 2. Inspect, measure, repair or replace oil pump, drives, pipes, and screens. 3. Inspect, repair or replace oil pressure regulator valve(s), by-pass valve(s), and filters. 4. Inspect, clean, test, reinstall or replace oil cooler, by-pass valve, oil thermostat, lines
and hoses. 5. Inspect turbocharger lubrication and cooling system; repair or replace components
as needed. 6. Verify engine oil level and condition; change engine oil and filter; select appropriate
oil type. 7. Inspect, reinstall or replace drive belts, pulleys and tensioners; adjust drive belts and
check alignment. 8. Verify coolant temperature and pressure; check operation of temperature/pressure and
level sensors/switches, temperature gauge, and sending unit. 9. Inspect, reinstall or replace cooling system thermostat(s), by-passes, housing(s), and
seals.
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10. Flush and refill cooling system; bleed air from system; recover coolant. 11. Inspect, repair or replace coolant conditioner/filter, check valves, lines, shutoff
valves, and fittings. 12. Inspect, repair, or replace water pump, hoses, idler pulley and drives. 13. Inspect radiator, pressure cap(s), and tank(s); determine needed service. 14. Inspect, repair or replace fan hub, fan(s), and fan clutch; inspect mechanical, hydraulic,
and electronic fan controls, fan thermostat, and fan shroud. 15. Pressure test cooling system and radiator cap(s); determine needed actions.
E. Air Induction and Exhaust Systems Diagnosis and Repair (7 questions) 1. Inspect, repair or replace air induction piping and clamps, air cleaner housing and
element(s); check for air restriction or contamination. 2. Inspect and test turbocharger, wastegate, actuator, and wastegate controls determine
needed actions. 3. Inspect and replace intake manifold and gaskets; test temperature and pressure
sensors; check connections. 4. Inspect, test, clean, repair or replace charge-air cooler (CAC), clamps, and
piping system. 5. Inspect, repair or replace exhaust manifold, gaskets, piping, mufflers, insulation/heat
shield and mounting hardware; inspect, replace, or service exhaust aftertreatment devices/catalytic converters and controls.
6. Inspect, test, and repair or replace O2 sensor(s), temperature sensors(s), EGR valve, EGR cooler and associated controls and wiring.
F. Fuel System Inspection, Diagnosis and Repair (14 questions) High Pressure Systems 1. Inspect fuel storage cylinders for physical damage, discoloration, delamination, and
leaks; inspect mountings, shields, and hardware; repair or replace as required. 2. Review vehicle maintenance/accident documentation; inspect and interpret cylinder
labels for cylinder compliance; determine needed action. 3. Inspect storage cylinder valves, solenoids, pressure relief device (PRD), fittings,
piping, clamps, check valves, and vent tubing; repair or replace as required. 4. Inspect fuel lines, clamps and fittings, fill receptacles, defueling receptacle, quarter-
turn valve/fuel shutoff valve, and high pressure gauge(s); repair or replace as required. 5. Inspect high pressure regulator, fuel filter, and coolant lines for leaks, proper
mounting or damage; determine needed action. 6. Service high-pressure regulator, fuel filter, coolant lines, hoses, and high-pressure
tubing as required. 7. Defuel cylinders; remove and replace cylinders. 8. Refuel system; check for leaks. 9. Properly decommission and dispose of cylinders.
Low Pressure Systems 10. Inspect low-pressure filter/housing, regulator, switch(s), sensor gauge, tubing, gaskets,
seals, and O-rings; determine needed action.
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11. Service low-pressure filter/housing, regulator, switch(s), sensor gauge, tubing, gaskets, seals, and O-rings as required.
Fuel Controls 12. Inspect fuel shutoff solenoids, throttle actuator, fuel metering devices, control valves,
and fuel mixer; repair or replace as required. 13. Inspect engine control module (ECM/ECU), sensors, wiring harness(s), connector(s)
and other modules; repair or replace as required.
G. Starting and Charging System Diagnosis and Repair (4 questions) 1. Perform battery state-of-charge test; determine needed service. 2. Perform battery load/capacitance tests; test battery cables for shorts, opens, and high
resistance. Determine needed service; repair as required. 3. Charge battery using slow or fast charge method as appropriate. 4. Start vehicle using jumper cables, a booster battery, or an auxiliary power supply. 5. Inspect, clean, repair or replace batteries, battery cables, battery disconnects, battery
hold-downs, and proper cable routing. 6. Inspect, test, or replace starter relays, interlock devices, safety switch(s), and solenoids. 7. Perform alternator amperage and voltage output tests; perform relay terminal output
voltage test; perform charging circuit voltage drop tests; verify battery equalizer operation; determine needed action.
8. Perform starter current draw and circuit voltage drop tests; determine needed action.
H. Ignition System Inspection, Diagnosis, and Repair (4 questions) 1. Diagnose ignition-related problems such as no-start, engine misfire, poor
drivability, spark knock, power loss, and poor mileage on vehicles with distributorless ignition systems; determine needed actions.
2. Check for possible ignition system related diagnostic trouble codes (DTC); verify performance parameters.
3. Inspect, test, repair or replace ignition primary circuit wiring and components. 4. Inspect and test spark plugs, boots, and wiring; verify spark plug gap. 5. Inspect, test, or replace ignition system secondary components. 6. Inspect, test, or replace ignition coil(s). 7. Inspect, test, or replace ignition system sensors. 8. Inspect, test, or replace ignition control module (ICM) or controller.
H1 TASk LiST (cOnTinuEd)
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1. A replacement pressure relief device (PRD) vent tube should be made of:
(A) rigid non-conductive material. (B) flexible plastic tubing. * (C) electrically conductive tubing. (D) copper tubing.
2. A transit bus with NGV Type 2 fuel tanks is being inspected. There is one 6” (15.24 cm) long cut measuring 0.008” (0.203 mm) deep in the outer covering of a tank. This tank should be:
* (A) considered useable as is. (B) rotated until the cut is on top. (C) repaired by removing and replacing the fiber wrap. (D) removed from service.
3. During operation, a transit bus has a puffing noise coming from the engine compartment. Which of these could be the cause?
(A) Faulty water pump * (B) Leaking exhaust manifold gasket (C) Leaking air intake (D) Faulty low-presure fuel regulator
4. Technician A says that the oil pressure can go too high if the oil pressure relief valve is stuck open.
Technician B says that the oil pressure can go too high if the engine is overfilled with lubricant.
Who is right?
(A) A only (C) Both A and B (B) B only * (D) Neither A nor B
SAmpLE QuESTiOnS cOmprESSEd nATurAL GAS EnGinES (TEST H1)
ASE TrAnSiT BuS STudy GuidE Page 15
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5. The voltage readings shown were taken while cranking the engine. Which of these is indicated by the readings?
(A) Battery #2 has resistance in the ground cable. * (B) Battery # 2 is weaker than battery #1. (C) Battery #1 is low on electrolyte. (D) Battery #2 should be replaced.
This question contains the word EXCEPT. Read the question carefully before choosing your answer.
6. A CNG transit bus with a normal range of 350 miles stops running after 3 hours. The high-pressure fuel gauge shows 375 psi. Any of these could be the cause EXCEPT for a:
(A) stuck cylinder flow control solenoid. (B) defective engine ECM wiring. (C) low CNG fuel cascade system pressure. * (D) defective high-pressure regulator.
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TEST SpEcificATiOnS And TASk LiST diESEL EnGinES (TEST H2)
Content Questions Percentage Area in Test of Test A. General Engine Diagnosis 14 28% B. Cylinder Head and Valve Train Diagnosis and Repair 4 8% C. Engine Block Diagnosis, Repair, and Overhaul 4 8% D. Lubrication and Cooling Systems Diagnosis and Repair 7 14% E. Air Induction and Exhaust Systems Diagnosis and Repair 6 12% F. Fuel System Diagnosis and Repair 11 22% 1. Mechanical Components (3) 2. Electronic Components (8) G. Starting and Charging System Diagnosis and Repair 4 7%
Total 50 100%
A. General Engine Diagnosis (14 questions) 1. Verify the complaint, and road test vehicle; review operator service request and past
maintenance documents (if available); determine further diagnosis. 2. Inspect engine assembly and engine compartment for fuel, oil, coolant, exhaust, or
other leaks; determine needed repairs. 3. Inspect engine compartment wiring harness, connectors, seals, and locks; check for
proper routing and terminal/connector condition; determine needed repairs. 4. Listen for and diagnose engine noises; determine needed repairs. 5. Check engine exhaust emissions, odor, smoke color, opacity (density) and quantity;
determine needed repairs. 6. Perform fuel supply and fuel return system tests; check fuel for contamination,
quality/type/grade, and consumption; determine needed repairs. 7. Perform air intake system restriction and leakage tests; determine needed repairs. 8. Perform intake manifold pressure tests; determine needed repairs. 9. Perform exhaust back-pressure and temperature tests; determine needed repairs. 10. Perform crankcase pressure test; determine needed repairs. 11. Diagnose no cranking, cranks but fails to start, hard starting, and starts but does not
continue to run problems; determine needed repairs. 12. Diagnose surging, rough operation, misfiring, low power, slow deceleration, slow
acceleration, and shutdown problems; determine needed repairs.
ASE TrAnSiT BuS STudy GuidE Page 17
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13. Isolate and diagnose engine related vibration problems; check engine mounts; determine needed repairs.
14. Check cooling system for temperature protection level, contamination, coolant type and level, temperature, pressure, supplemental coolant additive (SCA) concentration, filtration, and fan operation; determine needed repairs.
15. Check lubrication system for contamination, oil level, quality, temperature, pressure, filtration, and oil consumption; determine needed repairs.
16. Check, record, and clear electronic diagnostic codes; monitor electronic data; determine needed repairs.
17. Perform visual inspection for physical damage and missing, modified, or tampered components; determine needed repairs.
18. Research applicable vehicle and service information, service precautions, and technical service bulletins; determine needed actions.
B. Cylinder Head and Valve Train Diagnosis and Repair (4 questions) 1. Remove, inspect, disassemble, and clean cylinder head assembly(s). 2. Inspect threaded holes, studs, and bolts for serviceability; service or replace as
needed. 3. Measure cylinder head-to-deck thickness, and check mating surfaces for warpage and
surface finish; inspect for cracks and damage; check condition of passages; inspect core and gallery plugs; service as needed.
4. Inspect valves, guides, seats, springs, retainers, rotators, locks and seals; determine serviceability and needed repairs.
5. Inspect, reinstall or replace injector sleeves and seals; pressure test to verify repair (if applicable); measure injector tip or nozzle protrusion where specified by manufacturer.
6. Inspect, reinstall or replace valve bridges (crossheads) and guides; adjust bridges (crossheads).
7. Clean components; reassemble, check, and install cylinder head assembly as specified by the manufacturer.
8. Inspect, measure, reinstall, or replace pushrods, rocker arms, rocker arm shafts, and supports for wear, bending, cracks, looseness, and blocked oil passages. Visually inspect for wear and correct routing.
9. Inspect, install, and adjust cam followers. 10. Adjust valve clearances and injector settings. 11. Inspect, measure, and reinstall or replace overhead camshaft and bearings; measure
and adjust endplay and backlash.
C. Engine Block Diagnosis, Repair and Overhaul (4 questions) 1. Remove, inspect, service, and reinstall pans, covers, breathers, gaskets, seals, and
wear rings. 2. Disassemble, clean, and inspect engine block for cracks; check mating surfaces
for damage or warpage and surface finish; check deck height; check condition of passages, core, and gallery plugs; inspect threaded holes, studs, dowel pins and bolts for serviceability; service, reinstall or replace as needed.
Page 18 ASE TrAnSiT BuS STudy GuidE
3. Inspect cylinder sleeve counterbore and lower bore; check bore distortion; determine needed service.
4. Inspect and measure cylinder walls or liners for wear and damage; determine needed service.
5. Replace/reinstall cylinder liners and seals; check and adjust liner heights. 6. Inspect in-block camshaft bearings for wear and damage; replace as needed. 7. Inspect, measure, reinstall or replace in-block camshaft; measure and adjust end play;
inspect, reinstall or replace, and adjust cam followers (if applicable). 8. Clean and inspect crankshaft and journals for surface cracks and damage; check
condition of oil passages; check passage plugs; measure journal diameters; check mounting surfaces; determine needed service.
9. Inspect, reinstall or replace main bearings; check cap fit and bearing clearances; check and correct crankshaft endplay.
10. Inspect, reinstall, and time the drive gear train (check timing sensors, gear wear and backlash of crankshaft, camshaft, balance shaft, auxiliary drive, and idler gears); service shafts, bushings, and bearings.
11. Clean, inspect, measure, reinstall or replace pistons, pins, and retainers. 12. Measure piston-to-cylinder wall clearances. 13. Check ring-to-groove clearances and end gaps; install piston rings. 14. Identify piston, connecting rod bearing, and main bearing wear patterns that indicate
connecting rod and crankshaft alignment or bearing bore problems; check bearing bore and bushing condition; determine needed repairs.
15. Assemble pistons and connecting rods and install in block; check piston height; replace rod bearings and check clearances; check condition, position, and clearance of piston cooling jets (nozzles).
16. Inspect and measure crankshaft vibration damper; determine needed repairs. 17. Inspect, install, and align flywheel housing. 18. Inspect flywheel or flexplate (including ring gear) and mounting surfaces for cracks,
wear, and runout; determine needed repairs.
D. Lubrication and Cooling Systems Diagnosis and Repair (7 questions) 1. Verify engine oil pressure and check operation of pressure sensor, pressure gauge,
and sending unit. 2. Inspect, measure, repair or replace oil pump, drives, pipes, and screens. 3. Inspect, repair or replace oil pressure regulator valve(s), by-pass valve(s), and filters. 4. Inspect, clean, test, reinstall or replace oil cooler, by-pass valve, oil thermostat, lines
and hoses. 5. Inspect turbocharger lubrication system; repair or replace as needed. 6. Change oil and filter, verify oil level and condition. 7. Inspect, reinstall or replace drive belts, pulleys and tensioners; adjust drive belts and
check alignment. 8. Verify coolant temperature, and check operation of temperature and level sensors,
temperature gauge, and sending unit. 9. Inspect and replace cooling system thermostat(s), by-passes, housing(s), and seals. 10. Flush and refill cooling system; bleed air from system; recover coolant.
H2 TASk LiST (cOnTinuEd)
H2 TASk LiST (cOnTinuEd)
11. Inspect, repair or replace coolant conditioner/filter, check valves, lines, shutoff valves, and fittings.
12. Inspect, repair, or replace water pump, housing, hoses, idler pulley and drives. 13. Inspect radiator, pressure cap, and tank(s); determine needed service. 14. Inspect, repair, or replace fan hub, fan, and fan clutch; inspect mechanical, hydraulic,
and electronic fan controls, fan thermostat, and fan shroud. 15. Pressure test cooling system and radiator cap; determine needed repairs.
E. Air Induction and Exhaust Systems Diagnosis and Repair (6 questions) 1. Inspect, service or replace air induction piping, air cleaner, and element; check for
air restriction or contamination. 2. Inspect, test, and replace turbocharger, wastegate, and wastegate controls. 3. Inspect and replace intake manifold and gaskets; test temperature and pressure
sensors; check connections. 4. Inspect, test, clean, repair or replace aftercooler or charge-air cooler and piping
system. 5. Inspect, repair or replace exhaust manifold, gaskets, piping, mufflers, insulation/
heat shield and mounting hardware; inspect, replace, or repair exhaust aftertreatment devices
6. Inspect, repair or replace preheater/inlet air heater, starting aids, and controls. 7. Inspect, test, service, and replace EGR system components; including EGR valve,
variable ratio/geometry turbocharger, cooler, piping, filter, electronic sensors, controls, system air pressure solenoids, and wiring.
8. Inspect and repair exhaust brake system.
F. Fuel System Diagnosis and Repair (11 questions) 1. Mechanical Components (3 questions) 1. Inspect, repair or replace fuel tanks, vents, cap(s), mounts, valves, screens, crossover
system, supply and return lines, and fittings. 2. Inspect, clean, test, repair or replace fuel transfer pump, lift pump, drives, screens,
fuel/water separators/indicators, filters, heaters, coolers, ECM cooling plates, and mounting hardware.
3. Check fuel system for air and temperature; determine needed repairs; prime and bleed fuel system; check, repair or replace primer pump.
4. Inspect, test, repair or replace low/high pressure systems (check valves, pressure regulator valves and restrictive fittings).
5. Inspect, adjust, repair or replace mechanical engine throttle and controls. 6. Perform on-engine inspections, tests, adjustments, and time, or replace and time,
distributor-type injection pumps. 7. Perform on-engine inspections, tests, and adjustments, or replace mechanical unit
injectors. 8. Inspect, test, repair or replace fuel injection nozzles. 9. Inspect, adjust, repair or replace smoke limiters (air/fuel ratio controls).
Page 20 ASE TrAnSiT BuS STudy GuidE
10. Inspect, reinstall or replace high-pressure injection lines, fittings, seals, and mounting hardware.
11. Inspect, test, adjust, repair or replace engine fuel shut-off devices and controls, including engine protection shut-down devices, circuits and sensors.
2. Electronic Components (8 questions) 1. Check and record engine electronic diagnostic codes and trip/operational data; clear
codes; determine needed repairs. 2. Inspect, adjust, repair or replace electronic throttle and PTO (high/low idle) control
devices, circuits, and sensors. 3. Perform on-engine inspections, tests, and adjustments on hydraulic electronic unit
injectors (HEUI) and electronic controls (rail pressure control). 4. Perform on-engine inspections, tests, and adjustments on electronic unit injectors
(EUI) and electronic controls. 5. Inspect, test, adjust, repair or replace engine electronic fuel shut-down components,
circuits, and sensors, including engine protection and automatic stop systems. 6. Inspect and test voltage, ignition, and ground circuits and connections for electrical/
electronic components; determine needed repairs. 7. Inspect and replace electrical connector terminals, pins, harnesses, seals, and locks. 8. Connect diagnostic tool to vehicle/engine to access allowed service parameters;
determine needed repairs. 9. Use a diagnostic tool (hand-held or PC-based, and/or break-out cable or box) to
inspect and test electronic engine control system, sensors, actuators, electronic control modules (ECMs), and circuits; determine needed repairs.
10. Measure and interpret voltage, voltage drop, amperage, and resistance readings using a digital multimeter (DMM).
G. Starting and Charging System Diagnosis and Repair (4 questions) 1. Perform battery state-of-charge test; determine needed service. 2. Perform battery load and capacitance tests; determine needed service. 3. Charge battery using slow or fast charge method as appropriate. 4. Start vehicle using jumper cables, a booster battery, or an auxiliary power supply. 5. Inspect, clean, repair or replace batteries, battery cables, disconnects, and clamps. 6. Inspect, test, and reinstall or replace starter relays, safety switch(s), and solenoids. 7. Perform alternator voltage and amperage output tests; determine needed repairs. 8. Perform starter and charging circuit voltage drop tests; determine needed repairs.
H2 TASk LiST (cOnTinuEd)
ASE TrAnSiT BuS STudy GuidE Page 21
1. An operator complains that a transit bus has excessive black smoke when started in the morning. Which of these could be the cause?
* (A) A sticking fuel injector nozzle (B) A restricted fuel filter (C) A blocked fuel tank vent (D) A leaking fuel return line
2. An operator complains that a transit bus will not crank. This could be caused by:
(A) loose starter bolts. * (B) a failed starter solenoid. (C) a shorted starter ground cable. (D) the gear selector was left in neutral.
3. When the diesel engine in a transit bus reaches operating temperature, coolant flows out of the surge tank overflow tube.
Technician A says that air in the cooling system could be the cause. Technician B says that a failed radiator pressure cap could be the cause. Who is right?
(A) A only *(C) Both A and B (B) B only (D) Neither A nor B
4. During a cold weather start-up, the oil filter ruptures, causing an oil leak. This could be caused by:
* (A) a stuck-closed oil filter bypass valve. (B) a stuck-open oil pressure regulator valve. (C) use of a high viscosity motor oil. (D) excessive engine rpm at start-up.
5. A transit bus has had repeated serpentine belt failures. Which of these could be the cause?
(A) A stuck belt tensioner * (B) Misaligned belt pulleys (C) A binding idler bearing (D) An out-of-balance fan
SAmpLE QuESTiOnS diESEL EnGinES (TEST H2)
Page 22 ASE TrAnSiT BuS STudy GuidE
6. What is the technician checking in the illustration shown?
(A) Valve protrusion (B) Valve recession (C) Coolant nozzle recession * (D) Cylinder head warpage
7. Which of these can cause a no-start condition on a HEUI engine?
(A) High fuel pressure * (B) Low injection control pressure (C) High boost pressure (D) Low boost pressure
8. A diesel engine with EUI has a misfire and the check engine light is ON. Fault code “cylinder 4 current below normal” is active. This could be caused by a:
(A) failed engine position sensor. (B) sticking #4 injector plunger. * (C) broken #4 injector wire terminal. (D) sticking throttle position sensor.
This question contains the word EXCEPT. Read the question carefully before choosing your answer.
9. A transit bus has excessive engine oil consumption and an oil film on the back of the bus. All of these could be the cause EXCEPT:
(A) bad turbocharger seals. * (B) a cracked cylinder liner. (C) worn piston rings. (D) worn valve guide seals.
H2 SAmpLE QuESTiOnS (cOnTinuEd)
A. Automatic Transmission Diagnosis and Repair (28 questions) 1. Diagnose noise, vibration, and shifting problems; determine needed repairs. 2. Check transmission fluid level; check dipstick calibration; diagnose fluid usage,
leaks, and condition; determine needed repairs. 3. Perform transmission pressure tests; determine needed repairs. 4. Perform stall tests if applicable; determine needed repairs. 5. Perform lock-up converter system tests if applicable; determine needed repairs. 6. Replace fluid and internal/external filter(s). 7. Inspect, test, adjust, and/or replace retarder controls, valves, air lines, sensors, and
components. 8. Inspect and replace external seals and gaskets. 9. Inspect, test, and flush transmission cooler and lines; inspect breathers, filters, and
fittings; service as required. 10. Inspect, test, diagnose, adjust, repair, or replace electrical/electronic components
including the transmission control module(TCM), electronic modulators, solenoids, sensors (speed, temperature, pressure and level), relays, switches, lights, fuses/ breakers, wiring and connectors.
11. Inspect, replace, and align drivetrain mounts. 12. Remove and replace transmission; identify high voltage system if applicable; inspect
flywheel flex plate. 13. Inspect engine block, flywheel housing, and transmission mating surfaces; check
runout; check engine-to-transmission mounting adapters; determine needed repairs. 14. Perform high voltage disconnect procedure; reconnect/enable high voltage system. 15. Inspect, test, repair, or replace electronic shift selectors, switches, displays,
indicators, and wiring harnesses. 16. Diagnose automatic transmission and retarder problems using appropriate diagnostic
tools (laptop, shifter, etc.) and software, procedures, and service information/flow charts; check and record diagnostic trouble codes; clear codes; interpret digital multimeter (DMM) readings; determine needed repairs.
17. Diagnose failures in the data communications bus network; determine needed repairs.
TEST SpEcificATiOnS And TASk LiST drivE TrAin (TEST H3)
Content Questions Percentage Area in Test of Test A. Automatic Transmission Diagnosis and Repair 28 70% B. Drive Shaft and Universal Joint Diagnosis and Repair 4 10% C. Drive Axle Diagnosis and Repair 8 20%
Total 40 100%
Page 24 ASE TrAnSiT BuS STudy GuidE
B. Drive Shaft and Universal Joint Diagnosis and Repair (4 questions) 1. Diagnose driveshaft and universal joint noise and vibration problems; determine
cause of failure and needed repairs. 2. Inspect, service, or replace driveshaft, slip joints, yokes, drive flanges, universal
joints, and vibration dampers; phase drive shaft yokes. 3. Measure driveline angles; determine needed adjustments.
C. Drive Axle Diagnosis and Repair (8 questions) 1. Diagnose rear axle drive unit noise, vibration, and overheating problems; determine
needed repairs. 2. Check and repair fluid leaks; inspect and replace rear axle drive unit cover plates,
gaskets, breathers, magnetic plugs, and pinion seals. 3. Check rear axle drive unit fluid level and condition; determine needed service; add
proper type of lubricant. 4. Remove and replace differential carrier assembly, check ring and pinion backlash,
inspect rear axle housing mating surfaces; determine needed repairs. 5. Remove, inspect, and replace axle shafts. 6. Remove, inspect, and replace rear wheel hub assembly; inspect ABS tone/exciter ring
and wheel speed sensor; determine needed repairs. 7. Diagnose wheel bearing noises and damage; determine needed repairs. 8. Clean, inspect, lubricate, and replace wheel bearing cones and races (cups); clean
and inspect locking plates and nuts; replace seals, wear rings, and axle flange gasket; verify wheel bearing endplay and determine needed actions.
9. Inspect, adjust, repair, or replace planetary axle assemblies including case, idler pinion, pins, gears, thrust washers, shims, seals, cover, and springs.
H3 TASk LiST (cOnTinuEd)
ASE TrAnSiT BuS STudy GuidE Page 25
1. A transit bus with a diesel engine and an electronic automatic transmission shifts late. Which of these could be the cause?
(A) An illuminated “Do Not Shift” light (B) A failed retarder accumulator solenoid * (C) A failed throttle position (TP) sensor (D) A failed torque converter clutch (TCC) solenoid
2. An automatic transmission slips when cold, but shifts normally at operating temperature. Which of these could be the cause?
(A) A restricted transmission cooler (B) A misadjusted throttle position (TP) sensor * (C) Low fluid level (D) A worn converter hub
3. Which of these could cause the rear axle seals to fail repeatedly?
(A) Over-torqued wheel bearings * (B) A restricted axle housing breather (C) A high fluid level (D) Incorrect fluid type
4. A transmission has no lock-up. During a pressure test, no pressure is found at the lock-up test port. This could be caused by:
(A) lock-up clutch wear. (B) a locked stator. * (C) a bad lock-up solenoid. (D) a freewheeling stator.
5. A transit bus transmission is to be replaced. Technician A says that the transmission flex plate should be inspected each time the transmission is removed. Technician B says that the flywheel housing should be inspected each time the transmission is removed.
Who is right?
(A) A only * (C) Both A and B (B) B only (D) Neither A nor B
SAmpLE QuESTiOnS drivE TrAin (TEST H3)
Page 26 ASE TrAnSiT BuS STudy GuidE
6. An operator reports that the transit bus won’t go into gear. Technician A says that not engaging the high idle switch could be the cause. Technician B says that not stepping on the brake pedal could be the cause. Who is right?
(A) A only * (B) B only (C) Both A and B (D) Neither A nor B
H3 SAmpLE QuESTiOnS (cOnTinuEd)
7. What operation is being performed in the setup shown in the illustration?
(A) Adjusting tooth contact * (B) Checking ring gear runout (C) Checking ring gear backlash (D) Setting differential bearing
preload
This question contains the word EXCEPT. Read the question carefully before choosing your answer.
8. To most accurately check the fluid level in an automatic transmission, the technician should do all of these EXCEPT:
(A) park the transit bus on level ground. * (B) check while the fluid is cold. (C) put the transmission in NEUTRAL. (D) turn off the fast idle.
ASE TrAnSiT BuS STudy GuidE Page 27
TEST SpEcificATiOnS And TASk LiST BrAkES (TEST H4)
Content Questions Percentage Area in Test of Test A. Air Supply and Service Systems Diagnosis and Repair 24 48% B. Mechanical/Foundation Brakes Diagnosis and Repair 14 28% C. Parking Brakes Diagnosis and Repair 7 14% D. Wheel Bearings Diagnosis and Repair 5 10%
Total 50 100%
A. Air Supply and Service Systems Diagnosis and Repair (24 questions) 1. Diagnose poor stopping, pulling, grabbing, dragging, overheating, and air leak (static
and applied) problems, caused by supply and service system malfunctions; determine needed repairs.
2. Check air system build up and recovery time; determine needed repairs. 3. Inspect, repair or replace air reservoir tanks. Check for oil, water, and foreign
material. Check mounting brackets and hardware; determine needed repairs. 4. Inspect, adjust, align, or replace air compressor drive gears, and couplings. 5. Inspect, repair, or replace air compressor, air intake, oil and coolant lines and fittings. 6. Inspect, test, adjust, or replace system pressure controls (governor/ relief valve),
unloader assembly valves, pressure protection valves, and filters. 7. Inspect, repair, or replace air system lines, hoses, fittings, and couplings. 8. Inspect, test, clean, or replace air tank relief (pop off) valves, one way check valves,
drain cocks, automatic drain (spitter) valves, heaters, wiring, and connectors. 9. Inspect, clean, repair, or replace air drier systems, filters, valves, heaters, control
modules, wiring, and connectors. 10. Inspect, test, repair, or replace brake application (foot/treadle) valve, fittings, and
mounts; check and adjust brake pedal free play. 11. Inspect, test, clean, or replace two way (double) check valves and anti-compounding
valves. 12. Inspect, test, repair, or replace stop and parking brake light circuit switches, wiring,
and connectors. 13. Inspect, test, repair, or replace brake relay valve and quick-release valves. 14. Inspect, test, repair, or replace interlock system solenoid valves, regulator valves,
pressure switches, and related components. 15. Inspect, test, and replace inversion/emergency (spring) brake control valve(s). 16. Inspect, test, repair, or replace low-pressure warning devices.
Page 28 ASE TrAnSiT BuS STudy GuidE
H4 TASk LiST (cOnTinuEd)
17. Inspect, test, and replace air pressure sensors, gauges, lines and fittings. 18. Perform antilock brake system and automatic traction control (ABS/ATC) warning
lamp start-up test; determine needed repairs; retrieve diagnostic trouble codes (DTCs) using scan tool, PC computer, or LEDs; determine needed repairs.
19. Diagnose poor stopping and lockup problems on antilock brake systems (ABS); determine needed repairs.
20. Test, adjust, or replace antilock brake system (ABS) wheel speed sensors and tone/ exciter rings.
21. Test and replace antilock brake system (ABS) and automatic traction control (ATC) system, (ABS/ATC), electronic control units (ECU) and modulator valves, traction control valves; test, repair, and replace wiring and connectors.
22. Verify proper operation of auxiliary (transmission retarder, driveline, exhaust, and engine) braking systems.
B. Mechanical/Foundation Brakes Diagnosis and Repair (14 questions) 1. Diagnose poor stopping, brake noise, overheating, abnormal, premature wear,
pulling, grabbing, or dragging complaints caused by foundation brake, slack adjuster, and brake chamber problems; determine needed repairs.
2. Perform deceleration tests on service and parking brake systems. 3. Inspect, test, adjust, repair, or replace service brake chambers, diaphragm, clamp,
spring, pushrod, clevis, and mounting brackets. 4. Inspect, test, adjust, or replace automatic slack adjusters. 5. Inspect or replace S-cams, rollers, shafts, bushings, seals, spacers, and retainers;
lubricate as necessary. 6. Inspect, or replace brake spider, shields, anchor pins, shoe retainers, bushings, and
springs; lubricate as necessary. 7. Inspect, clean, adjust, or replace air disc brake caliper assemblies. 8. Inspect brake shoes, linings, or pads; determine needed repairs. 9. Inspect brake drums or rotors; determine needed repairs. 10. Resurface rotors brake drums and linings.
C. Parking Brakes Diagnosis and Repair (7 questions) 1. Inspect or replace parking (spring) brake chamber; dispose of removed brake
chambers in accordance with local regulations. 2. Inspect, test, or replace parking (spring) brake valves, lines, hoses, and fittings. 3. Manually release and cage parking (spring) brakes. 4. Inspect, test, and replace parking brake override valve. 5. Inspect, test, repair, or replace towing circuit components.
D. Wheel Bearings Diagnosis and Repair (5 questions) 1. Remove and replace axle hub and wheel assembly. 2. Clean, inspect, lubricate, or replace wheel bearing assemblies; replace seals and wear
rings. 3. Adjust axle wheel bearings in accordance with manufacturers’ procedures. 4. Inspect or replace extended service (sealed, close-tolerance, and unitized) bearing
assemblies; perform initial installation in accordance with manufacturers’ procedures. 5. Replace seals and O-rings on planetary axle assemblies; adjust axle endplay.
ASE TrAnSiT BuS STudy GuidE Page 29
SAmpLE QuESTiOnS BrAkES (TEST H4)
1. A transit bus, with a ruptured air supply tank, is being towed from the front. The technician should:
(A) prevent the steering wheel from turning. * (B) cage the rear air brake chambers. (C) drain the air from the secondary tank. (D) cage the front air brake chambers.
2. The setup in the illustration shows the first step in:
(A) measuring chamber pushrod travel. (B) adjusting spring brake tension. * (C) manually releasing the spring brake. (D) adjusting the brakes for lining wear.
3. The parking brakes fail to apply on a transit bus with air brakes. Technician A says that low air pressure in the spring brake chamber
could be the cause.
Technician B says that a ruptured spring brake diaphragm could be the cause.
Who is right?
(A) A only (C) Both A and B (B) B only * (D) Neither A nor B
Page 30 ASE TrAnSiT BuS STudy GuidE
4. The air line from the air drier to the air supply (wet) tank is being replaced.
Technician A says that there should be no low spots in the line after installation.
Technician B says that a smaller diameter line may be used for the replacement.
Who is right?
* (A) A only (C) Both A and B (B) B only (D) Neither A or B
5. A transit bus’ parking brake valve button pops out immediately after being depressed.
Technician A says this could be caused by low system air pressure.
Technician B says this could be caused by air in the emergency chamber.
Who is right?
* (A) A only (C) Both A and B (B) B only (D) Neither A nor B
6. A transit bus has an uneven braking problem. Which of these could be the cause?
(A) A binding treadle (foot) valve (B) Low brake line air pressure * (C) A failed brake drum (D) A failed governor
This question contains the word EXCEPT. Read the question carefully before choosing your answer.
7. An air compressor is not unloading, causing the air tank safety valve to pop off. This could be caused by any of these EXCEPT:
* (A) an obstructed intake. (B) a restricted governor reservoir line. (C) a bad governor. (D) a bad unloader.
H4 SAmpLE QuESTiOnS (cOnTinuEd)
ASE TrAnSiT BuS STudy GuidE Page 31
A. Steering System Diagnosis and Repair (12 questions) 1. Diagnose steering column (tilt, telescoping, or fixed) shaft noise, looseness, and
binding problems; determine needed repairs. 2. Inspect and replace steering shaft U-joint(s), slip joint(s), bearings, bushings, and
seals; phase steering shaft U-joints. 3. Diagnose hydraulic power steering system noises, steering binding, uneven turning
effort, looseness, hard steering, overheating, fluid leakage, and fluid aeration problems; determine needed repairs.
4. Diagnose electrical power steering system noises, steering binding, uneven turning effort, hard steering, unable to return to center, delay; determine needed repairs.
5. Inspect and replace electric steering assemly. 6. Inspect power steering fluid level and condition; determine fluid type and needed
service. 7. Purge air from the power steering system. 8. Perform power steering system pressure and flow tests; determine needed repairs. 9. Inspect, service, or replace power steering reservoir including filter, seals, and
gaskets. 10. Inspect, adjust, align, or replace power steering pump drive components. 11. Inspect power steering pump drive gear and coupling; replace as required. 12. Inspect, adjust, or repair power steering pump, mountings, and brackets; replace
as required. 13. Inspect power steering system cooler, lines, hoses, and fittings; replace as required. 14. Inspect power steering gear; replace as required. 15. Inspect and replace pitman arm; center the steering linkage. 16. Inspect, adjust/service, or replace drag link/center link, idler arm/stabilizer link, tie
rods and tie rod ends; position adjusting sleeves, clamps, and retainers. 17. Inspect steering and Ackerman/steering arms; replace as required.
TEST SpEcificATiOnS And TASk LiST SuSpEnSiOn And STEErinG (TEST H5)
Content Questions Percentage Area in Test of Test A. Steering System Diagnosis and Repair 12 27% B. Suspension Systems Diagnosis and Repair 23 51% C. Wheel Alignment Diagnosis, Adjustment and Repair 6 13% D. Wheels and Tires Diagnosis and Repairs 4 9%
Total 45 100%
Page 32 ASE TrAnSiT BuS STudy GuidE
18. Check and adjust steering gear poppet/relief valves, and wheel/steering stops. 19. Diagnose problems in the articulation system electronic controls, and mechanical and
hydraulic components; determine needed repairs.
B. Suspension Systems Diagnosis and Repair (23 questions) Independent Front Suspensions 1. Diagnose front suspension system noises, looseness, body sway, and ride quality;
determine needed repairs. 2. Inspect upper and lower control arms, strut rods/radius arms, bushings, shafts, and
rebound/jounce bumpers on short and long arm (SLA) suspension systems; replace as required.
3. Inspect kingpins and bushings/bearings; replace as required. 4. Inspect steering knuckle/spindle assemblies; replace as required. 5. Inspect, test and/or replace air bags; measure and adjust ride height. 6. Inspect stabilizer bar (sway bar) bushings, brackets, and links; replace as required. 7. Inspect shock absorbers, bushings, brackets, and mounts; verify adjustment; replace
as required.
Straight/I-Beam Axle Front Suspensions 8. Diagnose front suspension system noises, looseness, body sway, and ride quality;
determine needed repairs. 9. Inspect front axle, U-bolts, and fasteners; service or replace as required. 10. Inspect kingpins, steering knuckles, bushings, locks, bearings, shims, seals, and
covers; service or replace as required. 11. Inspect shock absorbers, bushings, brackets, and mounts; verify adjustment; replace
as required. 12. Measure vehicle ride height; determine needed adjustments or repairs. 13. Inspect, repair, and/or replace radius rods, lateral/torque rods, stabilizer bar (sway
bar), bushings, brackets, mounts, and air bags; adjust as necessary.
Rear Suspensions 14. Diagnose suspension system noises, looseness, ride quality, and body sway problems;
determine needed repairs. 15. Inspect rear axle housing, U-bolts, and fasteners; service or replace as required. 16. Inspect shock absorbers, bushings, brackets, mounts; verify shock absorber
adjustments; replace as required. 17. Measure vehicle ride height; determine needed adjustments or repairs. 18. Inspect and adjust rear axle alignment components such as radius rods, air/walking
beams, lateral rods, torque rods, stabilizer bars, and related bushings, mounts, shims, and links; replace as required.
Air Suspension System and Controls 19. Inspect, test, or repair/replace air bags/air springs, mounting plates, suspension arms,
and bushings. 20. Inspect, test, adjust, or repair air suspension pressure regulator, pressure protection
valve(s), leveling/height control valve(s), linkages, lines, hoses, and fittings; replace as required.
H5 TASk LiST (cOnTinuEd)
ASE TrAnSiT BuS STudy GuidE Page 33
21. Inspect and test operation of kneeling system; perform necessary repairs.
C. Wheel Alignment Diagnosis, Adjustment, and Repair (6 questions) 1. Diagnose vehicle wandering, pulling, shimmy, and steering effort problems;
determine needed adjustments or repairs. 2. Check and adjust camber; determine needed repairs. 3. Check and adjust caster; determine needed repairs. 4. Check SAI/KPI (steering axis inclination/kingpin inclination) and included angle;
determine needed repairs. 5. Check and adjust toe. 6. Diagnose toe-out-on-turns (Ackerman angle) problems; determine needed repairs. 7. Check rear axle alignment (thrust line/centerline) and tracking; adjust or determine
needed repairs. 8. Check and adjust axle wheel bearings.
D. Wheels and Tires Diagnosis and Repair (4 questions) 1. Diagnose tire wear patterns; determine needed repairs. 2. Inspect tires for damage; check and adjust tire pressure. 3. Diagnose wheel/tire vibration and shimmy problems; determine needed repairs. 4. Inspect and replace wheels (rims), studs, and nuts. 5. Measure wheel and tire runout (radial and lateral); determine needed repairs. 6. Balance wheel and tire assembly. 7. Measure tire diameter and/or circumference; match tires and rims.
H5 TASk LiST (cOnTinuEd)
Page 34 ASE TrAnSiT BuS STudy GuidE
1. Technician A says that when replacing a failed front wheel bearing, both bearings and races should be replaced along with the seals. Technician B says that when replacing a failed front wheel bearing, a front alignment should be performed. Who is right?
* (A) A only (C) Both A and B (B) B only (D) Neither A nor B
2. A transit bus has hard steering during sharp turns. Which of these could be the cause?
(A) Incorrect toe (B) Too much negative caster * (C) Misadjusted poppet/relief valves (D) Excessive power steering system pressure 3. A transit bus is leaning to the left in the rear. This could be caused by:
(A) low pressure from the supply reservoir. (B) low pressure at the rear accessory/suspension reservoir. (C) a faulty pressure protection valve. * (D) a faulty height control/leveling valve.
4. A transit bus operator reports that tight spots in the steering occur while turning the steering wheel. Technician A says that a binding steering column U-joint could be the cause. Technician B says that a worn tie rod end could be the cause. Who is right?
* (A) A only (C) Both A and B (B) B only (D) Neither A nor B
5. The operator says that the transit bus lift pan contacts the road surface when going over speed bumps. Which of these could be the cause?
(A) The system air pressure is too high. (B) The front of the bus is overloaded. * (C) The ride height needs to be adjusted. (D) The shock absorbers are too short.
SAmpLE QuESTiOnS SuSpEnSiOn And STEErinG (TEST H5)
ASE TrAnSiT BuS STudy GuidE Page 35
6. The operator could not keep the transit bus from wandering while driving at highway speeds. Technician A says that a 1/8” toe-in setting could be the cause. Technician B says that a worn tie-rod end could be the cause. Who is right?
(A) A only * (B) B only (C) Both A and B (D) Neither A nor B
H5 SAmpLE QuESTiOnS (cOnTinuEd)
7. Which of these is being measured in the setup shown in the illustration?
* (A) Steering shaft spline wear (B) Steering shaft out-of-roundness (C) Steering shaft diameter (D) Steering shaft endplay
This question contains the word EXCEPT. Read the question carefully before choosing your answer.
8. A transit bus has 120 psi air pressure shown at the dash panel gauge, but none of the air bag/springs will inflate. Any of these could be the cause EXCEPT a:
(A) leaking pressure protection valve. (B) stuck double-check valve. (C) leaking ACC/tank drain valve. * (D) stuck left rear height control/leveling valve.
Page 36 ASE TrAnSiT BuS STudy GuidE
TEST SpEcificATiOnS And TASk LiST ELEcTricAL/ELEcTrOnic SySTEmS (TEST H6)
Content Questions Percentage Area in Test of Test A. General Electrical/Electronic System Diagnosis 16 32% B. Battery and Starting System Diagnosis and Repair 12 24% C. Charging System Diagnosis and Repair 7 14% D. Lighting Systems Diagnosis and Repair 7 14% E. Related Vehicle Systems Diagnosis and Repair 8 16%
Total 50 100%
and/or road test vehicle; determine necessary action. 2. Check continuity in electrical/electronic circuits using appropriate test equipment. 3. Check applied voltages, circuit voltages, and voltage drops in electrical/electronic
circuits using a digital multimeter (DMM). 4. Check current flow in electrical/electronic circuits and components using an ammeter,
digital multimeter (DMM), or a clamp-on ammeter. 5. Check electronic circuit waveforms using an oscilloscope or graphing multimeter
(GMM); interpret readings and determine needed repairs. 6. Check resistance in electrical/electronic circuits and components using an ohmmeter
or a digital multimeter (DMM). 7. Locate shorts, grounds, and opens in electrical/electronic circuits. 8. Diagnose battery drain problems with the master/key switch OFF. 9. Inspect and test circuit breakers, solid state current limiters, and fuses; replace as
required. 10. Inspect and test spike suppression diodes/resistors and capacitors; replace as required. 11. Inspect and test relays and solenoids; replace as required. 12. Read and interpret electrical schematic diagrams and symbols. 13. Read and interpret ladder logic diagrams to diagnose electrical/electronic problems. 14. Read and interpret multiplex diagnostic LEDs; determine needed repairs. 15. Diagnose and repair computer communication multiplex systems; including
multiplex controllers, determine needed repairs.
ASE TrAnSiT BuS STudy GuidE Page 37
H6 TASk LiST (cOnTinuEd)
16. Using a laptop computer, establish communication with a multiplex control system. Verify that the needed ladder logic inputs are active to control an individual/specific ladder logic output.
17. Remove, replace, and adjust electrical/electronic switches, sensors, and other electrical/electronic components.
18. Use proper care and handling of electrical/electronic components. 19. Diagnosis failures in the controller area network (CAN) and determine needed
repairs.
B. Battery and Starting System Diagnosis and Repair (12 questions) 1. Perform battery load and/or capacitance tests; determine needed repairs. 2. Determine battery state of charge by measuring open circuit voltage (OCV) using
a digital multimeter (DMM). 3. Inspect, clean, and service battery, cables, terminal connections, and disconnects;
replace as required. 4. Inspect, clean, and repair battery boxes, mounts, and hold downs; replace as required. 5. Charge battery/batteries, using slow or fast charge method as appropriate. 6. Jump-start a transit bus using jumper cables and a booster battery or auxiliary power
supply. 7. Perform starter circuit voltage drop tests; determine needed repairs. 8. Inspect and test components of the starter control circuit (master/key switch, push
button and/or magnetic switch, and wires); replace as required. 9. Inspect and test starter, relays, and solenoids/switches; replace as required. 10. Remove and replace starter; inspect flywheel ring gear or flex plate. 11. Inspect, clean, repair or replace cranking circuit battery cables and connectors. 12. Differentiate between electrical, multiplex, or mechanical problems that cause a slow
cranking, no cranking, extended cranking, or a cranking noise condition.
C. Charging System Diagnosis and Repair (7 questions) 1. Diagnose the cause of no-charge, low-charge, or overcharge conditions; determine
needed repairs. 2. Inspect and adjust alternator drive belts/gears, pulleys, fans, air filters, centrifugal air
filters, mounting brackets, and tensioners; replace as required. 3. Perform charging system output tests (12 volt and 24 volt); determine needed repairs. 4. Perform charging circuit voltage drop tests; determine needed repairs. 5. Test, adjust, or replace voltage regulator. 6. Maintain, test, repair, remove, and replace alternator. 7. Inspect, repair, or replace charging circuit connectors and wires. 8. Check battery equalizer output, check wiring and mounting; determine needed
repairs. 9. Verify operation of charging system circuit monitor; determine needed repairs. 10. Differentiate between electrical, multiplex, or mechanical problems that cause
charging system malfunctions.
H6 TASk LiST (cOnTinuEd)
D. Lighting Systems Diagnosis and Repair (7 questions) 1. Diagnose the cause of brighter than normal, intermittent, dim, or no headlight and
daytime running light (DRL) operation. 2. Test, aim, and replace headlights. 3. Test headlight and dimmer switches, wires, connectors, terminals, sockets, relays, and
control components; repair or replace as required. 4. Inspect, test, and repair parking, clearance, and taillight circuit switches, bulbs,
sockets, connectors, terminals, relays, wires, and light-emitting diodes (LEDs); replace as required.
5. Inspect, test, and repair dash light circuit switches, bulbs, sockets, connectors, terminals, wires, and printed circuits; replace as required.
6. Inspect, test, and repair interior and exterior passenger light circuit switches, bulbs, sockets, connectors, terminals, ballasts/inverters, and wires; replace as required.
7. Inspect and test stoplight circuit switches, bulbs, light-emitting diodes (LEDs),sockets, connectors, terminals, relays, control components, and wires; repair or replace as required.
8. Diagnose the cause of turn signal and hazard light system malfunctions; determine needed repairs.
9. Inspect and test turn signal and hazard circuit flashers or other control components, switches, bulbs, sockets, connectors, terminals, relays, wires, and light-emitting diodes (LEDs); repair or replace as required.
10. Inspect and test backup light and warning devices, circuit switches, bulbs, light-emitting diodes (LEDs), sockets, connectors, terminals, and wires; repair or replace as required.
11. Differentiate between electrical, or multiplex problems that cause lighting system malfunctions.
E. Related Vehicle Systems Diagnosis and Repair (8 questions) 1. Diagnose the cause of intermittent, high, low, or no gauge readings; determine
needed repairs. 2. Diagnose the cause of control area network (CAN) driven gauge malfunctions;
determine needed repairs. 3. Inspect, test, and adjust gauge circuit sending units, sensors, gauges, connectors,
terminals, and wires; repair or replace as required. 4. Inspect and test warning device (lights and audible) circuit sending units, sensors,
bulbs, audible components, sockets, connectors, terminals, wires, and printed circuits/control modules; repair or replace as required.
5. Inspect and test electronic speedometer and odometer systems; replace as required; verify proper calibration for vehicle application.
6. Inspect and test horns, horn circuit relays, switches, connectors, terminals, and wires; repair or replace as required.
7. Diagnose the cause of constant, intermittent, or no wiper operation; diagnose the cause of wiper speed control and/or park problems.
8. Inspect and test wiper motor, resistors, park switch, relays, switches, connectors, terminals, and wires; repair or replace as required.
ASE TrAnSiT BuS STudy GuidE Page 39
9. Inspect and test windshield washer motor or pump/relay assembly, switches, connectors, terminals, and wires; repair or replace as required.
10. Inspect and test side view mirror motors, heater circuit grids, relays, switches, connectors, terminals, and wires; repair or replace as required.
11. Inspect and test HVAC electrical components including: A/C clutches, motors, resistors, relays, switches, controls, connectors, terminals, and wires; repair or replace as required.
12. Inspect and test engine cooling fan electrical control components; replace as required. 13. Differentiate between electrical, multiplex, or mechanical problems that cause body
system component malfunctions. 14. Inspect and test entrance door, controls, solenoids and switches, including Hall effect,
limit, reed and proximity switches and wires: repair or replace as required.
H6 TASk LiST (cOnTinuEd)
SAmpLE QuESTiOnS ELEcTricAL/ELEcTrOnic SySTEmS (TEST H6)
1. The headlights on a transit bus work OK on low beam, but they are very dim on high beam. Which of these could be the cause?
(A) A failed headlight ground (B) A failed ground at the master switch (C) An overloaded circuit breaker * (D) Corroded dimmer switch contacts
2. The operator notices battery odor while the transit bus is being driven. Which of these could be the cause?
* (A) The alternator is overcharging. (B) The electrolyte level is low. (C) The battery connections are loose. (D) The alternator drive belt is slipping.
3. Technician A says that a battery equalizer ensures that both batteries charge at the same rate.
Technician B says that a battery equalizer converts 24 volts to 12 volts in a 24-volt/two-battery system.
Who is right?
(A) A only (C) Both A and B * (B) B only (D) Neither A nor B
4. A transit bus’s windshield wipers work sporadically. Technician A says that an open (broken) wire could be the cause. Technician B says that a loose wiring connection could be the cause. Who is right?
(A) A only (C) Both A and B * (B) B only (D) Neither A nor B
ASE TrAnSiT BuS STudy GuidE Page 41
H6 SAmpLE QuESTiOnS (cOnTinuEd)
BRAKE SW
6. According to the ladder logic in the schematic shown, the MAG brake solenoid will release only when the:
(A) wheelchair power is on.
(B) “hi idle” is on. (C) park brake is applied. * (D) service brake is applied.
These questions contain the word EXCEPT. Read the questions carefully before choosing your answer.
7. When arc welding on a transit bus, a technician should disconnect all of these EXCEPT the:
(A) batteries. (B) engine control module. (C) transmission control module. * (D) starter.
8. All of these could cause high starter current draw EXCEPT:
(A) worn starter bushings. * (B) a failed starter relay. (C) grounded field coils. (D) a grounded armature.
5. An engine will not crank when the start button is pressed, but cranks normally when the starter relay is activated. Which of these could be the cause?
(A) A failed starter solenoid * (B) An open between the start button and the relay (C) A failed engine ground (D) An open between the battery and the relay
Page 42 ASE TrAnSiT BuS STudy GuidE
TEST SpEcificATiOnS And TASk LiST HEATinG, vEnTiLATiOn, And Air cOndiTiOninG
(TEST H7)
Content Questions Percentage Area in Test of Test A. A/C System and Component Diagnosis, Service and Repair 22 55% 1. A/C System—General (10) 2. Compressor and Clutch (6) 3. Evaporator, Condenser, and Related Components (6) B. Heating and Engine Cooling Systems Diagnosis, Service and Repair 8 20% C. Heating, Ventilation, and Air Conditioning Operating Systems and Related Controls Diagnosis and Repair 10 25% 1. Electrical/Electronic Systems (6) 2. Electronic Temperature Control System (4)
Total 40 100%
A. A/C System and Component Diagnosis, Service, and Repair (22 questions) 1. A/C System—General (10 questions) 1. Diagnose the cause of A/C system temperature control problems; determine needed repairs. 2. Identify HVAC system components and refrigerant type (R22, R134a, R407c); conduct performance tests; determine appropriate action.. 3. Diagnose the cause of A/C system problems indicated by temperature, pressure gauge readings, and sight glass/moisture indicator conditions (where applicable); determine needed service or repairs. 4. Diagnose the cause of A/C system problems by physical conditions (sight, sound, odor, and touch); determine needed repairs. 5. Perform A/C system leak test; determine needed repairs. 6. Evacuate A/C system using appropriate equipment.
Note: ASE HVAC certifications (A7, T7, H7 or S7) do not provide the necessary credentials to satisfy EPA requirements for Section 609 refrigerant management. The ASE Refrigerant Recovery and Recycling Review and Quiz program meets Section 609 requirements and can be taken online and in print. Details are at www.ase.com/cfc.
ASE TrAnSiT BuS STudy GuidE Page 43
H7 TASk LiST (cOnTinuEd)
7. Check and remove contaminants from the A/C system as needed. 8. Recover and recycle refrigerant; test for non-condensable gases. 9. Charge A/C system with refrigerant. 10. Identify A/C system lubricant type and amount needed for system application. 11. Use a computer and diagnostic software to read /clear fault codes, perform system tests; check and adjust system parameters; reprogram/flash ECM.
2. Compressor and Clutch (6 questions) 1. Inspect, diagnose, and test A/C system for problems that cause protection devices
(pressure, thermal, and electronic) to interrupt system operation; determine needed repairs.
2. Inspect, adjust, and align A/C compressor drives, belts, pulleys, and tensioners; replace as required.
3. Inspect, test, and service A/C compressor clutch components and clutch assembly; replace as required.
4. Check and correct A/C compressor lubricant level and condition; drain, refill, and install filter if needed.
5. Inspect and test A/C compressor operation and performance, including loaders and unloaders; check mountings and hardware; replace components as needed.
3. Evaporator, Condenser, and Related Components (6 questions) 1. Check and adjust A/C system lubricant level after replacement of system
components. 2. Inspect and repair A/C system hoses, lines, filters, fittings, and seals; replace as
required. 3. Check air flow through A/C condensers and evaporators; correct as required. 4. Inspect and test A/C system condenser and mountings; replace as required. 5. Inspect receiver and filter-drier; replace as required. 6. Inspect and test refrigerant solenoid, expansion valve(s), and evaporator pressure
regulators; check placement of thermal bulb (capillary tube); replace as required. 7. Inspect and test evaporator core; replace as required. 8. Inspect, clean, and repair evaporator housing and water drain; inspect and service or
replace evaporator air filter. 9. Identify and inspect A/C system service valves and connections; repair as required. 10. Diagnose cause of A/C system failures which result in refrigerant loss from the high
pressure relief valve.
B. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (8 questions) 1. Diagnose the cause of outlet air temperature control problems in the HVAC system;
determine needed repairs. 2. Diagnose window fogging problems; determine needed repairs. 3. Perform engine cooling system tests for leaks, freeze protection level, contamination,
coolant level, temperature, and conditioner concentration; determine needed repairs. 4. Inspect engine cooling and heating system hoses, lines, and clamps; replace as
required. 5. Inspect and test radiator, pressure relief devices, and coolant recovery system
(surge tank); determine needed repairs.
Page 44 ASE TrAnSiT BuS STudy GuidE
6. Inspect water pump and drive system; determine needed repairs. 7. Inspect and test thermostats, by-passes, housings, and seals; determined needed
repairs. 8. Flush and refill cooling system; bleed air from system. 9. Inspect and test fan, fan drives, controls, and fan shroud; repair or replace as required. 10. Inspect and test heating system coolant control valve(s) and manual shut-off valves;
replace as required. 11. Inspect and flush driver’s heater and/or defroster cores; replace as required. 12. Perform heating system tests to include coolant flow and booster pump(s) operation. 13. Inspect, test, and diagnose heater/defroster and defogger system problems; check
blowers, fans, resistors, switches, relay/modules, sensors, wiring, and protection devices; repair or replace as required.
14. Inspect, test and diagnose service heating, ventilating, and defrosting control panel assemblies, cables, and linkages; repair or replace as required.
15. Inspect, test, and diagnose heating, ventilating, and defrosting control switches, hoses, and solenoid valves; repair or replace as required.
16. Inspect, test, and adjust heating, ventilating, and defrosting ducts, filters, doors, hoses, and outlets; repair or replace as required.
C. Heating, Ventilation, and Air Conditioning Operating Systems and Related Controls Diagnosis and Repair (10 questions) 1. Electrical/Electronic Systems (6 questions) 1. Diagnose the cause of failures in HVAC electrical/electronic control systems; determine needed repairs. 2. Inspect and test HVAC defroster blower motors, resistors, switches, relays, modules, wiring, and protection devices; repair or replace as required. 3. Inspect and test HVAC compressor relays, modules, pressure transducers, wiring, sensors, switches, diodes, and protection devices; repair or replace as required. 4. Inspect and test HVAC evaporator/heater and condenser fan motors, motor drivers (alternating current and direct current), relays, modules, switches, sensors, wiring, and protection devices; repair or replace as required. 5. Inspect and test HVAC system electrical/electronic control panel assemblies; repair or replace as required.
2. Electronic Temperature Control Systems (4 questions) 1. Diagnose electronic temperature control system problems; determine needed repairs. 2. Inspect and test climate control temperature sensors; repair or replace as required. 3. Inspect and test coolant valve and controls; repair or replace as required. 4. Inspect and test solenoids and switches; repair or replace as required. 5. Inspect and test electronic temperature control panels and microprocessors; repair or
replace as required. 6. Connect computer using diagnostic software to read/clear fault codes and perform
system tests; check and adjust system parameters. 7. Inspect and test Controlled Area Network (CAN) for communication integrity.
H7 TASk LiST (cOnTinuEd)
SAmpLE QuESTiOnS HvAc (TEST H7)
1. High A/C discharge pressure can be caused by:
(A) restricted evaporator coils. * (B) an overcharged system. (C) a defective remote sensing bulb. (D) compressor oil overfill.
2. A technician cannot get a transit bus A/C system to take a refrigerant charge. Which of these could be the cause?
(A) Wrong compressor clutch clearance * (B) Suction service valve not mid-seated (C) Compressor speed too low (D) Excessive dirt in the system
3. Removing refrigerant from a system and storing it in a separate container is considered to be:
* (A) recovering. (B) evacuating. (C) reclaiming. (D) recycling.
4. An operator says that the HVAC system is not cooling properly. Air is blowing from the vents on one side of the transit bus only. This could be caused by:
(A) an undercharged system. * (B) one evaporator fan drive coupling being broken. (C) the evaporator fan turning too slowly. (D) the compressor clutch not being engaged.
5. Repeated A/C system high pressure hose failures can be caused by:
(A) extended operation of A/C with a loose drive belt. * (B) incorrect hose installation. (C) an open inside ambient air sensor. (D) extended operation of A/C in high humidity.
Page 46 ASE TrAnSiT BuS STudy GuidE
6. Both the suction-side and discharge-side pressures are above normal. This could be caused by:
(A) a stuck-closed coolant modulating valve. (B) the compressor clutch not disengaging. * (C) a dirty condenser core. (D) a too-slow evaporator fan speed.
7. Before being recharged, an A/C system should be evacuated to:
(A) 29 in. Hg. for 2 hours. (B) 30 in. Hg. for 30 minutes. * (C) 500 to 1500 microns for 10 minutes. (D) 2500 to 3000 microns for 30 minutes.
8. Reusable refrigerant cylinders must be hydrostatically tested every:
(A) year. (B) 3 years. * (C) 5 years. (D) 10 years.
9. An operator complains of a coolant smell while running the defroster. Which of these could be the cause?
(A) A closed shutoff valve (B) A failed defroster switch * (C) A leak in the defroster core (D) A leak in the evaporator core
This question contains the word EXCEPT. Read the question carefully before choosing your answer.
10. A transit bus has thrown its A/C compressor drive belts for the second time. Any of these could be the cause EXCEPT:
(A) the compressor’s isolator mounts are worn out. (B) the compressor and engine crankshaft pulleys are out
of alignment. (C) a weak automatic belt tensioner. * (D) excessive air gap at the A/C clutch armature.
H7 SAmpLE QuESTiOnS (cOnTinuEd)
TEST SpEcificATiOnS And TASk LiST prEvEnTivE mAinTEnAncE And inSpEcTiOn
(pmi) (TEST H8)
Content Questions Percentage Area in Test of Test A. Engine Systems 17 34% B. Body Interior and Exterior 5 10% C. Electrical/Electronic Systems 9 18% D. Frame and Chassis 19 38%
Total 50 100%
A. Engine Systems (17 questions) Engine 1. Check engine operation for unusual noises, vibration, and exhaust smoke. 2. Inspect crankcase ventilation system. 3. Inspect belts, tensioners, belt guards, pulleys and alignment; check and adjust belt
tension; inspect vibration damper. 4. Check engine compartment for oil, coolant, air, hydraulic fluid, fuel and diesel
exhaust fluid (DEF) leaks; check oil line routing and mounting (Engine Off and Engine Running).
5. Inspect engine mounts for looseness and deterioration. 6. Check engine oil pressure, oil level and condition; check dipstick seal. 7. Check engine compartment wiring (low and high voltage), harnesses, connectors
and seals; check for proper routing and damage; check engine compartment controls, gauges, diagnostic lights and compartment lighting.
Fuel System 8. Check fuel tanks and mountings, filler neck; check valve mountings, lines, vents, and
caps. 9. Drain water and contaminants from fuel system. 10. Inspect water separator/fuel heater; replace fuel filter(s); prime and bleed fuel system.
Air Induction and Exhaust Systems 11. Inspect diesel emission control systems and components, including exhaust gas
recirculation (EGR), catalytic converter, and diesel particulate filter (DPF). 12. Check engine exhaust system mountings for looseness and damage. 13. Check engine exhaust system for leaks, excessive noise, proper routing, and missing
or damaged components (heat shields and guards). 14. Check air induction system routing, piping, charge air cooler, hoses, clamps,
mountings, and indicators; check for air restrictions and leaks.
Page 48 ASE TrAnSiT BuS STudy GuidE
15. Inspect turbocharger for noise and leaks; check mountings and connections; check wastegate and controls, variable geometry turbo, linkages, and hoses.
16. Connect diagnostic tool/laptop, check for exhaust system codes, check past repair history, check exhaust aftertreatment health; determine needed actions.
17. Service or replace air filter(s) as required.
Cooling System 18. Check operation of fan system (including electrical and hydraulic systems); check
for hydraulic leaks; inspect wire harness and connectors, inspect fan assembly, fan shroud, and mountings.
19. Inspect radiator and hydraulic oil cooler for air flow restrictions, leaks, and damage; check mountings.
20. Pressure test cooling system and radiator cap. Check cooling system for leaks; determine needed repairs.
21. Inspect all coolant and hydraul